PSI - Issue 44

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Marianna Leonori et al. / Procedia Structural Integrity 44 (2023) 1022–1029 Author name / Structural Integrity Procedia 00 (2022) 000–000

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3. New retrofitting strategies using 3D print Additive Manufacturing technology In recent years, 3D polymeric materials printing has been becoming quite common. Instead, the 3D steel printing has become more common only recently. The innovation process within Edil CAM Sistemi Srl will lead to the production of certified stainless-steel components by 3D printing. Contrary to traditional mechanical manufacturing, additive manufacturing allow to overcome the complexity of the component shape, turning it into an advantage. The 3D printing system used is a metal binder jetting system that prints, layer by layer, customer-ready, high-resolution parts with incredibly fine feature detail. For example, for the UNI-CAM anchor plate, the 3D printing system can produce many benefits using less raw material compared with traditional subtractive manufacturing. This kind of production overcomes many design constraints, producing parts with complex geometry, limiting the environmental footprint and without additional cost. 3.1. CAM ® technology for the evolution of ancient tie rods As mentioned before, reinforcements which are commonly and architecturally accepted include tie rods. The CAM ® System is already a system of tying, capable of “packaging” the masonry structure. Ancient tie rods and anchor plates on historical structures, which are allowed by the Ministry of Cultural Heritage, always remain completely visible and become an element of architectural value. With 3D printing and the evolution of CAM ® tie rods, the end anchor plate element could be "drawn" in the style of the building. The evolution of CAM ® tie rods consists of a bundle of ribbons in the central part and two ending parts connected using linking elements. The two ending parts reach the walls under the arch or at the top of the columns. The ribbons bundle tensioning can be calibrated and re-calibrated over time.

Fig. 9. CAM® evolution for tie rods

The main evolution is in the ending part. In fact, in ancient tie rods those end parts were the only elements that locally stressed the masonry. Instead, with the new CAM ® solution, the ending parts are both constraints and also a confining element. Furthermore, each ending part could be separated into two or more rings in order to reduce local stress. Anchor plates can easily be hidden under plaster or recessed into the wall. The linking element that must join the ribbons bundle to the ending part can be designed adopting the 3D topological approach. In this way, it is possible to balance mechanical resistance and aesthetic shape, while minimizing weight and relative cost. 3.2. The new post tensioning system T-CAM The latest main innovative product currently being worked on by Edil CAM Sistemi Srl is the new closure and tensioning system applied to strips. The recently patented tensioner, called T-CAM , is an element that allows strips to be joined simultaneously with high precision tuning tensioning and without resistance reduction. It can be revamped over time and is also usable